The first Labor hopeful for the New South Wales Central Coast seat of Dobell held by embattled Independent MP Craig Thomson is a former Liberal Party member.

Labor will hold a rank-and-file preselection ballot for its notionally held seat three months before the federal election on September 14 and former Liberal Party member Trevor Drake has confirmed he will nominate.

Nominations opened today and the vote will be held on June 29.

Mr Drake, a solicitor and former Gosford Councillor who has lived and worked in Long Jetty for 17 years, believes he would represent the people of Dobell well.

Mr Drake says he understands the needs and concerns of local residents, and he expressed his opposition to the Wallarah 2 coal project near Wyong, which is operated by South Korean mining company Kores.

"If I was preselected I'd be campaigning in pushing Labor values for Dobell and looking after the interests of the electorate and also Kores coal mine, which Mr Thompson has been championing to date - I think that needs to be pushed further as well," Mr Drake said.

Mr Thomson, who has held the seat since 2007, resigned from the Australian Labor Party last month to recontest Dobell as an independent in the September poll.

The ABC understands there is no obvious ALP frontrunner for the ballot.

The winner will take on Mr Thomson and the Liberals' Karen McNamara.

Mr Thomson is facing 173 charges relating to allegations he misused Health Services Union (HSU) funds on hospitality and prostitutes while he was national secretary between 2002 and 2007.

He was suspended from Labor in April last year after Fair Work Australia completed a long-running investigation into the allegations.

Mr Thomson denies any wrongdoing and is fighting the allegations in court.